Residual, or locked-in internal, stresses are regions of misfit within a metal part or assembly that can cause distortion and fracture just as can the more obvious applied, or service, stresses. This chapter describes the fundamental facts about residual stresses and discusses the basic mechanisms of residual stress formation: thermal, transformational, mechanical, and chemical.

This chapter provides an overview of factors that must be considered in the design of structural components for satisfactory service performance in terms of mechanical behavior of steel castings. The chapter discusses designing against yielding, excessive deflection, and creep and stress rupture. The chapter describes the three main approaches to evaluating and designing structures relative to fatigue resistance: the S-N curve approach for high cycle fatigue, the strain range approach for low cycle fatigue, and the fracture mechanics approach. Two approaches to design against brittle fracture are described, the ductile to brittle transition concept and the fracture mechanics approach. The chapter also discusses several types of corrosion behavior and emphasizes the need to interact with corrosion specialists in the design process. It illustrates the unique advantages that designers may gain by designing components as castings to achieve low stress concentrations economically.

This chapter is a compilation of terms and definitions related to component failure analysis.

This chapter is a compilation of terms and definitions related to component failure analysis.

Elevated-temperature failures are the most complex type of failure because all of the modes of failures can occur at elevated temperatures (with the obvious exception of low-temperature brittle fracture). Elevated-temperature problems are real concerns in industrial applications. The principal types of elevated-temperature failure mechanisms discussed in this chapter are creep, stress rupture, overheating failure, elevated-temperature fatigue, thermal fatigue, metallurgical instabilities, and environmentally induced failure. The causes, features, and effects of these failures are discussed. The cooling techniques for preventing elevated-temperature failures are also covered.

This chapter discusses the most common causes and contributing factors for external corrosion and stress-corrosion cracking on oil and natural gas pipelines, as well as describes procedures for prevention, mitigation, detection, assessment, and repair. The forms of external corrosion covered include differential cell corrosion, microbiologically influenced corrosion, and stray current corrosion.

This chapter covers the failure modes and mechanisms associated with boiler components and the tools and techniques used to assess damages and predict remaining component life. It begins with a review of the design and operation of a utility boiler and the materials used in construction. It then describes the various causes of failure in boiler tubes, headers, and steam pipes, explaining how and why they occur, how they are diagnosed, and how to mitigate their effects. The final and by far largest section in the chapter is a tutorial on damage and life assessment techniques for boiler components and assemblies. It demonstrates the use of various methods, including analytical techniques that estimate life expenditure based on operating history, component geometry, and material properties; predictive methods based on the extrapolation of failure statistics; methods that predict life based on dimensional measurements; methods based on metallographic studies; methods based on temperature estimates; and a method for estimating remaining life under creep conditions based on stress-rupture testing of service-exposed material samples. The chapter also discusses the use of fracture mechanics and presents a number of cases in which life assessments are made based on the integration of several methods.

The chapter presents an overview of the properties and operational limits of superconductive materials, as well as techniques used to fabricate practical superconducting wires. It introduces six properties: critical temperature, critical magnetic field, critical current density, stability, ac loss, and mechanical characteristics; for each property, typical data are provided and the experimental methods used to measure it are briefly described. The properties of the superconducting composites are tied together in the chapter to summarize their effect on superconductor material selection and the geometrical design of superconducting composites. The chapter also contains a reference guide to composite-design factors with links to the relevant chapter sections where each design consideration is addressed.

This chapter is largely a compendium of best practices and procedures for minimizing the effects of fatigue. It explains how to make products more resistant to fatigue by choosing the right materials and manufacturing processes, avoiding geometries and features that concentrate strains, preventing or removing surface damage, and by inducing compressive mean stresses that prolong fatigue life. It also discusses the use of property conditioning and restoration treatments, the benefits of interference fits and processes such as coaxing, the effects of assembly damage and operating overload, the importance of surface cleanliness and finish, and the role of inspection, testing, replacement, and repair in safe-life and fail-safe designs. Examples highlighting the benefits and potential pitfalls of proof loading tests are included as well.

This chapter outlines the major types of corrosion, their interactions, their complicating effects on fracture and wear, and some possible prevention methods. The types of corrosion considered in the chapter are galvanic corrosion, uniform corrosion, pitting corrosion, crevice corrosion, microbiologically influenced corrosion, stress-corrosion cracking, and corrosion fatigue.

This chapter provides a detailed overview of the creep behavior of metals and how to account for it when determining the remaining service life of components. It begins with a review of creep curves, explaining how they are plotted and what they reveal about the operating history, damage mechanisms, and structural integrity of the test sample. In the sections that follow, it discusses the effects of stress and temperature on creep rate, the difference between diffusional and dislocation creep, and the use of time-temperature-stress parameters for data extrapolation. It explains how to deal with time dependent deformation in design, how to estimate cumulative damage under changing conditions, and how to assess the effect of multiaxial stress based on uniaxial test data. It also includes information on rupture ductility, creep fracture, and creep-crack growth and their effect on component life and performance.

This chapter discusses the use of mechanical fastening and adhesive bonding, the primary methods for joining polymer matrix composites. It describes and analyzes the basic types of mechanically fastened joints, including single-hole and multirow bolted composite joints. It then reviews the advantages and disadvantages of adhesively bonded joints and compares and contrasts the long-term performance of various joint designs. The chapter also discusses the merits of stepped-lap and bonded-bolted joints.

Environmentally assisted cracking is a generic term that includes various cracking phenomena such as stress-corrosion cracking (SCC), corrosion fatigue cracking, and liquid-metal embrittlement. This chapter describes these cracking mechanisms beginning with SCC and the factors that influence its formation. It covers alloy selection and mitigation techniques and includes examples of SCC in aircraft components. The chapter also addresses corrosion fatigue, explaining how different environments and operating conditions affect crack propagation, fatigue strength, and fatigue life. It includes information on liquid-metal embrittlement as well.

This article introduces the subject of fractography and how it is used in failure analysis. The discussion covers the structure of and fracture and crack-propagation behavior of polymeric materials, the distinction between the ductile and brittle fracture modes on the basis of macroscopic appearance, and the examination and interpretation of the features of fracture surfaces. In addition, the article considers several cases of field failure in various polymers to illustrate the applicability of available analytical tools in conjunction with an understanding of failure mechanisms.

The power generating industry has become proficient at predicting how long a component will last under a given set of operating conditions. This chapter explains how such predictions are made in the case of boiler tubes. It identifies critical damage mechanisms, progressive failure pathways, and relevant test and measurement procedures. It describes life assessment methods based on hardness, wall thickness, scale formation, microstructure, and creep. It also includes a case study on the determination of the residual life of a secondary superheater tube.

This chapter describes important requirements for ferrous and nonferrous alloys used for gears. Wrought surface-hardening and through-hardening carbon and alloy steels are the most widely used of all gear materials and are emphasized in this chapter. The processing characteristics of gear steels and the bending fatigue strength and properties of carburized steels are reviewed. In addition to wrought steels, the chapter provides information on the other iron-base alloys that are used for gears, namely cast carbon and alloy steels, gray and ductile cast irons, powder metallurgy irons and steels, stainless steels, and tool steels. In terms of nonferrous alloys, the chapter addresses copper-base alloys, die cast aluminum alloys, zinc alloys, and magnesium alloys.